1 Answer

If you shut off the power and turn it back on does it start and run? if so, replace you air filter. Odds are the blower is dirty and if it is dirty the secondary heatexchanger is dirty and if you have a/c your a-coil will most likely be a bit dirty too. And it all starts with the ducts, there is only one place the dirt comes from. This causes bad air flow over time and could be causing your problem. But in order to do this have a hvac company come in and clean it. Find someone who does furnace and duct cleanings. I own a heating, cooling and duct cleaning business and see this all the time. a way to check the air flow is to take the return tempature and the plenum tempature. if the unit is running on high it prob should be around 70-75F diff. The sticker inside the furnace will tell you the proper temp rise.

Now if the rool out switch on the side of the burner box is tripped call a tech and have them check the heat exchanger. a burner tube is most likley gone, but this is very unlikely.

1 Suggested Answer

Look at the electrical schematic on the inside cover to the electrical compartment. It should have a list of fault codes. Locate the condesate drain lines (up to three) and remove them and inspect them for debris/blockage. Clean them and flush them with warm water and clorox solution. Make sure that your condensate line is not blocked and that you are getting drainage from the condensate line. The new high efficiency furnaces generate a great deal of condensate water from the burner and it needs to drain properly.

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The flame sensor can still be faulty, replacing that is the cheapest. Other issues could be a faulty control board (if available), a faulty gas valve, thermostat lossing call, or a safety/pressure switch problem. There are alot of variables and it really helps to have a meter to check voltage and continuity through-out the system.

Look at the electrical schematic on the inside cover to the electrical compartment. It should have a list of fault codes. Locate the condesate drain lines (up to three) and remove them and inspect them for debris/blockage. Clean them and flush them with warm water and clorox solution. Make sure that your condensate line is not blocked and that you are getting drainage from the condensate line. The new high efficiency furnaces generate a great deal of condensate water from the burner and it needs to drain properly.

You could have plugged orfices in the line coming out of the gas valve. Next you could have a plugged gas regulator.The only way your going to find this out is to check gas pressure before the gas valve during a call for heat and then check it after the gas valve during a call for heat you could have a bad gas valve. Try this let me know what you find Thanks and please leave feedback

Hi,
One of the limit switch in the furnace is tripped or went bad....
Try to find all of the reset switches and push the little red button on the top to reset them...
If that don't work you will need to take an electric meter and test each switch to see which one is bad...

the wire diagram should tell you how. it all depends where wires lead to. be very carefull, capacitors can be dangerous. brown usaully go to fan black usaully goes to common red usaully goes to herm or compressor. it all depends where wires come from

I have an old York outside compressor/coil/fan unit, CDHF36-6A, that I need to replace as it is no longer repairable. What is the capacity of this unit and what Carrier unit would be a good replacement?